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of Massachusetts Department
ENVIRONMENTAL PROTECTION
MassDEP Waste Site Cleanup
Advisory Committee
Advances in Characterization:
Continuous VOC data
November 2018
John Fitzgerald, MassDEP
of Massachusetts Department
ENVIRONMENTAL PROTECTION
“Data is good”
More Data = Better Characterization
More data is always helpful…..
…sometimes essential
of Massachusetts Department
ENVIRONMENTAL PROTECTION
The New Frontier: Continuous VOC Data
How: automated gas chromatographs
Time per analysis: < 10 minutes (typical)
Data points/day: 6/hr x 24 = 144
Data points/project: do the math
Neat option: view data real-time via internet
of Massachusetts Department
ENVIRONMENTAL PROTECTION
Why?
To characterize air with substantial temporal
variability
Such as?
Indoor air (vapor intrusion)
Ambient/indoor air @ construction/remedial
projects at highly contaminated sites near
homes/school
of Massachusetts Department
ENVIRONMENTAL PROTECTION
TCE in soil
@ 11,000 mg/kg
Chelsea High
School
N
HVAC Intake
of Massachusetts Department
ENVIRONMENTAL PROTECTION
Release Abatement Measure – Spring 2018
Take 1: PID monitoring only
Take 2: On-site Gas Chromatograph
TCE @ fence-line > 24 µg/m3 = test school air
TCE in school > 24 µg/m3 = Imminent Hazard
(Periodic 1-Liter bag grab samples)
of Massachusetts Department
ENVIRONMENTAL PROTECTION
Release Abatement Measure – Spring 2018
Control vapors:
Shut down/button up site
water/foams/poly sheeting
< 40 minutes of exceeding 24 µg/m3 TCE @ fenceline
of Massachusetts Department
ENVIRONMENTAL PROTECTION
Release Abatement Measure – Spring 2018
April 9th
Excavation begins
April 18th
> 200 µg/m3 of TCE detected at fence-line
April 19th
> 4000 µg/m3 TCE detected at fence-line
> 600 µg/m3 TCE detected outside school building
of Massachusetts Department
ENVIRONMENTAL PROTECTION
April 19th
MassDEP samples/analyzes air samples inside school
Up to 79 µg/m3 TCE detected within school building
School building evacuated
Construction job shut down
Release Abatement Measure – Spring 2018
of Massachusetts Department
ENVIRONMENTAL PROTECTION
Plan B TCE
of Massachusetts Department
ENVIRONMENTAL PROTECTION
Continuous TCE Monitoring
GC/ECD (SRI)
8 minute sample run (looking only at TCE)
4 sampling ports:
Cafeteria
3rd floor
Outside air
Calibration check standard (TCE @ 5.4 µg/m3)
of Massachusetts Department
ENVIRONMENTAL PROTECTION
Continuous TCE Monitoring
Less-conservative Action Levels:
TCE concentrations inside high school cannot
exceed 8 µg/m3 over an 8 hour exposure period
(which would constitute Significant Risk)
No single concentration of TCE can exceed 24 µg/m3
(due to concern of exceeding 8 hour average limit)
of Massachusetts Department
ENVIRONMENTAL PROTECTION
Continuous TCE Monitoring
Work resumed 6/21/18 and continued until 8/23/18
Continuous 24/7 analyses
each port sampled every 8 minutes
Over 8000 TCE data points
Work was halted on a number of occasions due to
rising TCE concentrations in the outdoor and indoor air
TCE levels in school never posed an Imminent Hazard
– and the data log proves it!
of Massachusetts Department
ENVIRONMENTAL PROTECTION
TCE Data - July 20, 2018 Outside air
Cafeteria
3rd Floor
12 µg/m3 @ 7:30 AM
5.2 µg/m3 @ 10 AM
5.8 µg/m3 @ 9:45 AM
6 AM 2 PM
of Massachusetts Department
ENVIRONMENTAL PROTECTION
Advantages of Continuous Air Monitoring
• Early-warning of rising contaminant levels in outdoor
and indoor air, to allow job modifications or shut
down prior to exceeding safe levels
• Piece-of-mind for building occupants (and
regulators!) who can access data 24/7 via the
internet, and view real-time and logged data
• Eliminates need to set conservative shut-down and
evacuation levels based on only a few data points